(1) Field of the Invention
The present invention relates to the field of seats for aircraft, and in particular rotorcraft. The present invention relates more particularly to the structural organization of a bench providing safety for passengers in the event of the aircraft being subjected to a high level of deceleration and/or in the event of a crash, by providing protection against the deformation of at least one wall of the aircraft on which the bench is fastened.
(2) Description of Related Art
It should be understood below that the concept of “longitudinal” and the associated concept “longitudinally-extending bar”, the concept of “transverse”, and the associated concept of “transverse-member”, and the concepts of “vertical”, “horizontal”, “front”, “rear”, “base”, “low”, and “high”, for example, are concepts that are relative and identified with respect to the dimensions in which the bench under consideration extends in a situation of use by a passenger conventionally installed on the bench.
Seats for aircraft incorporate means for protecting passengers installed on those seats in the event of the aircraft crashing. More particularly, an aircraft seat is commonly organized to compensate for the deformation of a wall of the aircraft on which the seat is fastened and/or for absorbing the energy that results from the forces to which the seat carrying the passenger is generally subjected in the event of the aircraft suffering a high level of deceleration.
For this purpose, an aircraft seat is conventionally arranged as a structure that is deformable at a predetermined threshold for the force to which the seat is subjected, and/or that is fitted with energy absorber means suitable for compensating the stresses to which the seat is subjected when suffering violent impacts and/or in the event of the aircraft being subjected to a high level of deceleration.
Aircraft seats include benches organized as a support structure carrying a framework on which bucket seats or “buckets” are fastened. An advantage of such benches is to enable a plurality of buckets to be installed on board the aircraft while using a common support structure of weight and size that are small compared with installing seats individually, each having a single bucket.
The support structure is fitted with anchor members for anchoring to at least one wall of the aircraft, the anchor members together defining an installation plane for the bench on board the aircraft. The support structure commonly includes a pair of longitudinally-extending bars that extend in the long direction of the bench, said bars carrying the framework and together defining a bucket support plane that extends substantially parallel to the plane on which the bench is installed.
The wall of the aircraft on which the support structure is anchored is commonly formed by a floor having the support structure fastened thereto via at least one underframe having means for fastening it to the floor on its base. By way of example, the underframe is fastened to the floor by bolts or via fittings that co-operate with rails incorporated in the floor.
The wall of the aircraft on which the support structure is anchored may also potentially be formed by a structural wall of the fuselage of the aircraft to which the support structure is fastened at at least one of its longitudinal ends.
For example, the support structure may be provided at one of its longitudinal ends with first fastener means for fastening to a structural wall of the aircraft fuselage and at its other longitudinal end with an underframe having second fastener means for fastening to the floor of the aircraft.
Each bucket is dedicated to receiving a single passenger, and conventionally each is formed by a one-piece unit comprising a seat proper with a back extending upwards therefrom, the seat and the back typically being oriented at a dihedral angle relative to each other.
The framework conventionally comprises a set of supports for buckets arranged in succession in alignment along the long direction of the bench as defined by the general direction in which the bars extend. Conventionally, the supports are carried jointly by the longitudinally-extending bars in their front portions and in their rear portions. The supports are commonly arranged as single-piece angle members, each constituted by an upright-member and by a transverse-member forming a dihedral angle between each other matching the dihedral shape of the buckets.
The buckets are fastened on two neighboring supports by being installed side by side on the framework in succession along the long direction of the bench, the seat and the back of each bucket being fastened to respective branches of each of two adjacent said angle members.
In that context, there are various difficulties that need to be overcome in order to make safe passengers who are installed on the bench in the event of the aircraft being subjected to a high level of deceleration and/or being involved in a crash, while still ensuring suitable comfort for the passengers when the seat is in ordinary use, and indeed possibly optimizing such comfort.
Such difficulties lie in the context of an on-going search for reducing the weight of a bench while also optimizing the number of buckets that can be installed on the support structure for a bench of given size.
Except in an aircraft crash situation, i.e. in a situation of ordinary use of the bench, each of the support structure and/or the framework constitutes a unit that is robust and not deformable.
In order to protect the passengers installed on the bench in the event of the aircraft crashing, it is known to hinge the framework to the support structure so as to allow the framework to move relative to the support structure when the bench is subjected to a predefined force threshold. Such hinged mounting of the framework is conventionally achieved via longitudinally-extending bars, such as by hinged mounting of the supports on the bars or of the bars on the support structure.
With a bench of such an architecture, the framework is allowed to move relative to the support structure in the event of the support structure deforming as a result of the aircraft crashing and causing the support structure to be subjected to forces greater than said force threshold due to deformation of said at least one wall of the aircraft on which the support structure is fastened.
Still for the purpose of protecting passengers in the event of the aircraft crashing, it is also known to interpose energy absorber means between various members of the bench. By way of example, such energy absorber means may be interposed between the framework and the support structure, between the buckets and the framework, or indeed between structural elements of the support structure.
Such energy absorber means are constituted in particular by means that are deformable at a predetermined threshold and they are known in the field of seats for aircraft. On this topic, reference may be made for example to the following documents: FR 2 683 191 (Israel Aircraft Ind. Ltd.), DE 4 312 343 (Eurocopter Deutschland), and FR 2 950 607 (Eurocopter France).
Concerning passenger comfort in an ordinary use situation of the bench, it is also desirable for the architecture of the bench to allow the dihedral angle formed between the seat and the back of each bucket to be modified and to allow the height position of each seat to be adjusted. Naturally, such arrangements must not interfere with the robust and non-deformable nature of the support structure and/or of the framework in the absence of the aircraft being in a crash situation.
It is also desirable in an ordinary use situation of the bench for the architecture of the bench to lead to no impediment for passengers installed on the bench concerning another bench placed in front of them. It is in particular advantageous for passengers installed on one bench to be able to stretch their legs, while still enabling two adjacent benches to be installed as close as possible one in front of the other. For this purpose, it is desirable for the space under the bench to be sufficiently unencumbered to be able to receive the lower limbs of a rear passenger.
Numerous bench architectures have been proposed in the context of the above-mentioned search for improved seats. For example, reference may be made to the following documents: EP 0 423 348 (Shigeru Kiguchi et al.), U.S. Pat. No. 5,657,950 (Ind. Technology Research Int. et al.), U.S. Pat. No. 4,718,719 (E. J. Brennan et al.), CN 101 492 095 (He Caifu et al.), WO 2012/053618 (Delta Tooling Co. Ltd.), WO 92/19464 (Koito Kogyo KK), U.S. Pat. No. 6,669,143 (Glenn Johnson), and U.S. Pat. No. 4,487,383 (Bernard Mazelsky).